Disabled retroviruses-fossils of molecular battles that raged for generations-make up eight per cent of the human genome.

Social bookmarking is a way for Internet users to store, organize, share and search bookmarks of web pages. In a social bookmarking system, users save links to web pages that they want to remember and/or share. These bookmarks are usually public, but depending on the service's features, may be saved privately, shared only with specific people or groups, shared only inside certain networks, or another combination of public and private. The allowed people can usually view these bookmarks chronologically, by category or tags, via a search engine, or even randomly.